我有一种情况,我正在验证一个用于启用按钮的文本框。如果文本框为空,则应禁用该按钮,反之亦然。如果我在 XAML 后面的代码中编写逻辑,我可以处理代码并实现解决方案,但我觉得那不是正确的方式,应该从 viewModel 而不是后面的代码处理事件。
这是我所做的:
XAML
<TextBox Grid.Row="1" Margin="6,192,264,0" Height="60" VerticalAlignment="Top"
x:Name="txtDNCNotes" Text="{Binding Path=DNCNotes, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
TextWrapping="Wrap" VerticalScrollBarVisibility="Auto"
Visibility="{Binding Path=DNCNoteTxtVisibility}" Grid.Column="1"
behaviour:TextBoxFilters.IsBoundOnChange="True"
TextChanged="TextBox_TextChanged" />
视图模型
public string DNCNotes
{
get { return _dncNotes; }
set {
if (_dncNotes == value) return;
_dncNotes = value;
OnPropertyChanged("DNCNotes");
}
}
背后的代码
private void TextBox_TextChanged(object sender, TextChangedEventArgs e)
{
var ctx = LayoutRoot.DataContext as NextLeadWizardViewModel;
BindingExpression binding = txtDNCNotes.GetBindingExpression(TextBox.TextProperty).UpdateSource();
ctx.ShowDoNotContact();
}
我正在尝试在 viewModel 中编写以下代码来实现解决方案,但不确定要写什么。
public void ShowDoNotContact()
{
Binding myBinding = new Binding("DNCNotes");
//myBinding.Source = DataContext as NextLeadWizardViewModel;
myBinding.Source = txtDNCNotes;
myBinding.Path = new PropertyPath("DNCNotes");
myBinding.Mode = BindingMode.TwoWay;
myBinding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
BindingOperations.SetBinding(txtDNCNotes, TextBox.TextProperty, myBinding);
if (_dncNotes == null)
OkCommand.IsEnabled = false;
else
OkCommand.IsEnabled = CanEnableOk();
}